Audio oscillator design still practical?

Discussion in 'The Projects Forum' started by upand_at_them, Apr 4, 2015.

  1. upand_at_them

    Thread Starter Active Member

    May 15, 2010
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    I could find use for this on my test bench: http://www.redcircuits.com//Page82.htm

    But I see that the design comes from the 1980's. Is it still worth building? How does it compare to the cheap DDS modules available now? And what about building an adjustable Wein bridge? Should I shutup, build it, and see for myself?
     
  2. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
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    The numbers look good and it claims to be from a respected source. Still worth building, in my opinion.
     
  3. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    The NE5532 and TL084 are pretty good opamps.
    The stability is made with the LED(D5)/LDR(R9) combination.
    Put them together in a light tight box.

    Bertus
     
  4. OBW0549

    Well-Known Member

    Mar 2, 2015
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    Who knows? Only one way to find out, and that's to build it and see. Nothing wrong with designs from the 1980's, unless they relied on obsolete components for proper operation.

    I'm not familiar with those, but DDS as a sine wave generation technique has (when done right) a couple of outstanding characteristics: extreme frequency accuracy and stability due to the low cost of accurate, stable crystal oscillators, and absolute repeatability. When these qualities are important, DDS stands head and shoulders above any other technique. DDS is not too good for getting very low THD at low frequencies, though, because of the limited resolution (often no more than 10 bits) of the synthesis DAC.

    A Wein bridge oscillator would work just fine.

    The "build it and see" part is good. I don't like the "shutup" part, though; I'd like to hear what kind of results you get from this circuit.

    Meanwhile, here's a good application note on sine wave generation techniques:

    http://www.ti.com/lit/an/snoa665c/snoa665c.pdf
     
  5. upand_at_them

    Thread Starter Active Member

    May 15, 2010
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    Okay, good. Do you think I can get away with building it on protoboard and point-to-point wiring? (I've never done a PCB design.)
     
  6. Brownout

    Well-Known Member

    Jan 10, 2012
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    Download LTSpice and simulate it before building it. Make sure it works as advertised, and explore the functionality before going to all the trouble.
     
  7. upand_at_them

    Thread Starter Active Member

    May 15, 2010
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    I'm about to place a parts order through Tayda. They have everything except the 220pF 63V Polystyrene capacitors. The only thing that's close is 220pF 50V Monolithic Ceramic. Does it really need to be polystyrene?
     
  8. bertus

    Administrator

    Apr 5, 2008
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    simo_x likes this.
  9. upand_at_them

    Thread Starter Active Member

    May 15, 2010
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    Thanks, it looks like C0G is the way to go.
     
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